Combine the confectioners' sugar, cocoa powder, milk powder, salt, cornstarch in a large airtight container. Secure the lid and shake vigorously to combine, and remember to shake prior to every use.
TO SERVE:
Place 2 tablespoons of the mix in a mug and add about 2 fluid ounces hot water or milk. Stir to combine. Fill the mug with more hot water or milk and enjoy.